$\mathit{d}$-Band Quantum Well States

Observations of $d$-band quantum well states are made for atomically uniform Ag films on Fe(100) using angle-resolved photoemission. For increasing film thicknesses, quantum well peaks within the small $4d$ bandwidth multiply rapidly and merge into a bulklike spectrum at $\sim 25$ monolayers. An analysis of the peak positions yields a highly accurate bulk band structure of Ag. A very narrow $d$-band peak width (13 meV) is observed at the band top.